近端串音 1.近端串音的推导对称电缆的近端串音基本上是随机性的。由于四线组内两回路导线距离近,小的线距偏离便会产生较大的耦合。而组间的两回路导线距离较大,由导线或介质的随机性原因产生的耦合较小。所以组间的近端串音通常小于组内。此外,由于两四线组的绞合节距不同,等于在 Near-end crosstalk 1. Derivation of near-end crosstalk Near-end crosstalk of a symmetrical cable is essentially random. Due to the distance between the two loop conductors in the four-wire group, the small line deviations will produce a large coupling. However, the distance between the two loop wires in the group is relatively large, and the coupling caused by the randomness of the wires or the medium is small. So the near-end crosstalk between groups is usually smaller than the group. In addition, due to the twisting pitch of the two or four wire groups, equal to